A capillary electrophoresis device fills a separation medium (which is a buffer solution or a buffer solution containing a screening polymer solution) in a molten silica capillary tube of inner diameter 100 μm or less, and places a sample at one end of the capillary tube, which is separated inside the capillary tube by high voltage applied across the capillary tube. For stabilizing the separation in the capillary tube, the device controls its surrounding temperature precisely. An optical method such as fluorescence analysis or an electrochemical method detects the components of an analyzing object separated in the capillary tube at the other end of the capillary tube.
Introducing a sample into the capillary tube may be carried out by pressure injection from one end or pressure reduction from the other end, and additionally, if a highly viscous separation medium is filled in the capillary tube, an electric filling method which introduces a sample into the capillary tube by applying high voltage across the capillary tube whose one end contacts with a sample solution. (For example, refer to Patent Article 1).
The electric method for filling a sample into a capillary tube introduces a predetermined amount of sample into the capillary tube which is filled with a separation medium by connecting one end of the capillary tube (called the detection end) to a buffer solution reservoir (called the anode reservoir) which contains a buffer solution, and at the same time the other end of the capillary tube (called the injection end) is immersed in a sample storage unit, so that a certain value of electric potential difference may be applied across two electrodes each of which is immersed in the anode reservoir and the sample storage unit respectively for a certain time period.
After introducing the sample into the capillary tube, the injection end is immersed in the reservoir (i.e., the cathode reservoir) which stores a buffer solution, and electrophoresis of the sample is carried out by applying voltage between both electrodes while each of them is immersed in the anode reservoir and the cathode reservoir, respectively.